A house on Bell Street has caught fire for the second time in seven months.
Two crews of Whanganui firefighters arrived at the scene on Tuesday afternoon to discover a well-involved fire at the rear of the property and extinguished it in approximately 10 minutes.
Whanganui station officer Bryan Coskerie said the fire was being treated as suspicious.
"It was an unoccupied home so there's no real reason any fire should have started," Coskerie said.
"The fire's extinguished, we've got the fire investigator here, she's going into have a look and see what's happened."